Adsorption process for recovering easy-to-regenerate condensible components from a multicomponent gas stream

ABSTRACT

The present invention relates to an improved cyclic adsorption process for recovering easy-to-regenerate condensible components from a multi-component gas stream. After contact with the inlet gas stream the adsorbent bed or beds containing easy and difficult-to-regenerate components are regenerated by contact with a lean regeneration gas stream. The resulting rich regeneration gas stream is contacted with a liquid stream consisting primarily of easy-to-regenerate components so that a major portion of the difficult-to-regenerate components contained therein are absorbed and removed by the liquid stream. The remaining rich regeneration gas stream is cooled so that easy-toregenerate components and additional difficult-to-regenerate components contained therein are condensed thereby producing the liquid stream comprised primarily of easy-to-regenerate components used to contact the rich regeneration gas stream and a lean regeneration gas stream of a minimum difficult-to-regenerate component content. The lean regeneration gas stream is heated and recirculated in a closed circuit into contact with the bed or beds being regenerated thereby causing a maximum quantity of the difficult-to-regenerate components to be removed from the bed or beds and maximum bed easy-to-regenerate component adsorption capacity to be realized.

United States Patent Young et al.

Inventors: Gary Clifford Young, Pawhuska;

Joseph A. Kleinpeter, Ponca City, both of Okla.

Continental Oil Company, Ponca City, Okla.

Filed: April 2, 1971 Appl. No.: 130,691

Assignee:

US. Cl ..55/62 Int. Cl. ..B01d 53/04 Field of Search ..55/62, 179

References Cited UNITED STATES PATENTS 4/1966 Lavery et al ..55/62Primary Examiner-Charles N. Hart Attorney-Joseph C. Kotarski, Henry H.l-luth, Robert B. Coleman, .lr., Gerald L. Floyd and Caroll PalmerABSTRACT adsorption process for recovering easy-to-regeneratecondensible components from a multi-component gas stream. After contactwith the inlet gas stream the adsorbent bed or beds containing easy anddifficult-toregenerate components are regenerated by contact with a leanregeneration gas stream. The resulting rich regeneration gas stream iscontacted with a liquid stream consisting primarily ofeasy-to-regenerate components so that a major portion of thedifficult-toregenerate components contained therein are absorbed andremoved by the liquid stream. The remaining rich regeneration gas streamis cooled so that easyto-regenerate components and additionaldifficult-toregenerate components contained therein are condensedthereby producing the liquid stream comprised primarily ofeasy-to-regenerate components used to contact the rich regeneration gasstream and a lean regeneration gas stream of a minimum difficult-toregenerate component content. The lean regeneration gas stream is heatedand recirculated in a closed circuit into contact with the bed or bedsbeing regenerated thereby causing a maximum quantity of thedifiicult-to-regenerate components to be removed from the bed or bedsand maximum bed easy-toregenerate component adsorption capacity to berealized.

8 Claims, 1 Drawing Figure in 2a ll? BACKGROUND OF THE INVENTION 1.Field of the Invention The present invention relates to an improvedadsorption process for recovering condensible components from amulti-component gas stream, and more particularly, but not by way oflimitation, to a cyclic adsorption process of the type wherein one ormore beds of solid adsorbent are contacted with an inlet gas stream sothat condensible components are adsorbed thereon, then contacted by aheated regeneration gas stream so that the components are desorbed fromthe bed or beds and then contacted with a cooling gas stream preparatoryto again being contacted with the inlet gas stream.

2. Description of the Prior Art Many various vapor adsorption processeshave been developed of the type wherein one or more beds are utilizedfor adsorbing condensible components from a gas stream while the otherbeds are being regenerated. Regeneration of the bed or beds which aresaturated with condensible components is accomplished by heating the bedor beds with a heated regeneration gas stream which causes thecondensible components to be desorbed from the bed. The desorbedcomponents are then condensed and removed from the regeneration gasstream. The hot bed which has been regenerated is cooled by contactingit with a cooling gas stream preparatory to again being contacted withthe inlet gas stream. The various gas streams are continuously switchedor cycled so that the bed or beds which have just contacted the inletgas stream are contacted with the heated regeneration gas stream, thebed or beds which have just been contacted with the heated regenerationgas stream are contacted with the cooling gas stream, and the bed orbeds which have just been contacted with the cooling gas stream arecontacted with the inlet gas stream.

Commonly, adsorption process of the type described herein are used forrecovering desired condensible components from a multi-component gasstream containing both easy-to-regenerate and difficult-toregenerateadsorbable condensible components. That is, some of the adsorbablecomponents contained in the gas stream are readily removed from theadsorbent by the contact thereof with a heated regeneration gas stream,while other of the components require extensive contact of the adsorbentwith the heated regeneration gas stream before they are desorbed andremoved. For example, natural gas usually contains adsorbablehydrocarbon compounds which are relatively easy to regenerate, such asmethane and ethane, as well as adsorbable hydrocarbon compounds whichare increasingly difficult to regenerate, such as propane, butanes andheavier hydrocarbon compounds. In an adsorption process wherein a bed ofadsorbent is contacted with a multi-component gas stream containing bothdifficult and easy-to-regenerate adsorbable componentsfiall of theadsorbable components are adsorbed on the bed to some degree. The mostdifficult-to-regenerate components are adsorbed vigorously and the otheradsorbable components are adsorbed to a lesser extent in the order oftheir degree of difficulty to regenerate. For example, when an adsorbentsuch as activated carbon is contacted witha gas stream containingmethane, ethane and propane, the propane is adsorbed more vigorouslythan ethane, with methane being adsorbed to a lesser degree. When theactivated carbon is regenerated by contact with a heated regenerationgas stream the adsorbed hydrocarbon compounds such as propane are moredifficult to desorb than ethane with methane the easiest to desorb.

It has heretofore been recognized that the most effective regenerationof an adsorbent bed with a heated regeneration gas stream isaccomplished with a lean regeneration gas stream. That is, aregeneration gas stream as devoid of the components to be desorbed fromthe bed or beds as possible achieves the most effective regeneration.Heretofore, in order to obtain as lean a heated regeneration gas streamas possible for contacting the adsorbent beds, systems utilizing closedregeneration gas stream circuits have been utilized. The term closedcircuit is used herein to mean a system of conduits, valves, pumps,etc., within which a gas stream is continuously recirculated without thecontinuous addition or removal of gas therefrom. The condensiblecomponents desorbed into the regeneration gas stream as it contacts theadsorbent are condensed and removed therefrom, and the resulting leanregeneration gas stream is heated prior to being recirculated throughthe adsorbent. However, even where a closed regeneration gas streamcircuit is used, the lean regeneration gas stream remaining afterdesorbed components have been condensed and separated therefrom containsquantities of both the easy and difficult-toregenerate components due tothe well known vaporliquid equilibrium behavior of multi-componentsystems. Further, because the lean regeneration gas stream containsdifficult-to-regenerate components, a relatively high regeneration gasstream rate and/or contact time is required to removedifficult-to-regenerate components absorbed on the bed or beds beingregenerated. This problem becomes particularly difficult in applicationswhere an adsorption process of the type herein described is utilized forrecovering easy-to-regenerate components from a multi-component gasstream containing both difficult and easyto-regenerate components. Inorder to adsorb a major portion of the easy-to-regenerate componentscontained in the inlet gas stream, the cycle time, i.e., the time theinlet gas stream is allowed to contact each adsorbent bed, must belimited. This is because the difficult-to-regenerate components areadsorbed most readily on the bed, and with increasing contact time thequantity of difficult-to-regenerate components adsorbed on the bedincreases thereby reducing the bed adsorption capacity foreasy-to-regenerate components. Due to this limited cycle time incombination with difficult-to-regenerate components being contained inthe regeneration gas stream, adequate regeneration of the adsorbent isdifficult to achieve, and over a period of time adsorbeddifficult-toregenerate components build up on the adsorbent reducing itscapacity for easy'to-regenerate com- ,ponents thereon.

' By the present invention, an improved adsorption process forrecovering easy-to-regenerate components from a multi-component gasstream is provided wherein the desorbed condensible components areremoved from the rich regeneration gas stream in a manner such that alean regeneration gas stream of minimum difficult-to-regeneratecomponent content is produced.

SUMMARY OF THE INVENTION The present invention relates to an adsorptionprocess for recovering easy-to-regenerate condensible components from amulti-component inlet gas stream wherein a fixed adsorbent bed iscontacted with the inlet gas stream so that both difficult andeasy-toregenerate condensible components contained therein are adsorbedon the bed, then contacted with a heated lean regeneration gas stream sothat the adsorbed components are desorbed therefrom into theregeneration gas stream, the desorbed condensible components beingcondensed and removed from the rich regeneration gas stream therebyproducing a lean regeneration gas stream and then contacted with acooling gas stream so that it is cooled preparatory to again contactingthe inlet gas stream.

By the present invention desorbed condensible components are removedfrom the rich regeneration gas stream by intimately contacting the richregeneration gas stream with a liquid stream consisting primarily ofcondensed easy-to-regenerate components so that a portion of thedifficult-to-regenerate components contained therein are absorbed andremoved therefrom by the liquid stream. The liquid stream is withdrawnfrom the process and the remaining rich regeneration gas stream iscooled so that easy-to-regenerate and additional difficult-to-regeneratecondensible components contained therein are condensed. The condensedcomponents are separated from the regeneration gas stream therebyproducing a lean regeneration gas stream of minimumdifficult-to-regenerate component content and the liquid streamconsisting primarily of easy-toregenerate components which is used tocontact the rich regeneration gas stream.

It is, therefore, an object of the present invention to provide animproved adsorption process for recovering easy-to-regeneratecondensible components from a multi-component gas stream.

A further object of the present invention is the provision of animproved adsorption process wherein the lean regeneration gas stream isof a minimum difficultto-regenerate component content thereby achievingmaximum removal of difficult-to-regenerate components from the adsorbentbed being regenerated.

Other and further objects, features and advantages of the presentinvention will be apparent from the following description of presentlypreferred embodiments of the invention, given for the purpose ofdisclosure and taken in conjunction with the accompanying drawing.

DESCRIPTION OF THE DRAWING In the drawing, one system which may be usedfor carrying out the improved process of the present invention isillustrated in diagrammatic form.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing, asystem which may be used for carrying out the improved process of thepresent invention is illustrated in diagrammatic form and generallydesignated by the numeral 10. An inlet multicomponent gas streamcontaining easy-toregenerate condensible components to be recoveredenters the system 10 by way of the conduit 12. The conduit 12 isconnected to an inlet gas header 14 from where the inlet gas stream isrouted to one of three vessels l6, l8 and 20, each of which contains astationary bed of solid adsorbent material. A variety of commerciallyavailable adsorbent materials well known to those skilled in the art maybe utilized in the system 10. For example, adsorbent materials such asactivated carbon, activated alumina and a variety of silica compoundsare commonly used for adsorbing condensible hydrocarbon components fromnatural gas streams. Conduits 28, 30 and 32 are connected to the inletconnections of the vessels 16, 18 and 20, respectively, and to the inletgas stream header 14. Valves 22, 24 and 26 are disposed in the conduits28, 30 and 32, respectively. A residue gas outlet header 34 is providedconnected to the outlet connections of the vessels 16, 18 and 20 byconduits 36, 38 and 40, respectively. Valves 42, 44 and 46 are disposedin the conduits 36, 38 and 40. The main residue gas header 34 isconnected to a conduit 48 which conducts the residue gas from the system10 to a point of use of further processing.

A closed regeneration gas stream circuit for continuously regeneratingone of the adsorbent beds contained within the vessels 16, 18 and 20 isprovided. A conventional gas stream heater 50 is provided in theregeneration gas stream circuit having a coil 52 disposed therein. Theregeneration gas stream inlet header 55 is connected to the outletconnection of the heating coil 52 by conduit 53. The header 55 isconnected by conduits 54, 56 and 58 to conduits 28, 30 and 32respectively. Valves 60, 62 and 64 are disposed in the conduits 54, 56and 58 respectively. A regeneration gas stream outlet header 66 isprovided for receiving the rich regeneration gas stream from the vessels16, 18 and 20. Conduits 68, 70 and 72 are connected to the header 66 andto the conduits 36, 38 and 40. Valves 74, 76 and 78 are disposed in theconduits 68, 70 and 72, respectively. The header 66 is connected by aconduit 80 to a conventional rich regeneration gas-lean regeneration gasheat exchanger 82. The rich regeneration gas stream outlet of the heatexchanger 82 is connected by a conduit 84 to the lower portion of avessel 88 containing a plurality of conventional vapor-liquid contacttrays 90. The gas outlet connection of the vessel 83 is connected by aconduit 92 to a conventional gas cooler 94. The discharge connection ofthe cooler 94 is connected to a conventional vapor liquid separator 96by a conduit 98. Liquid separated in the separator 96 is conducted tothe upper portion of the vessel 88 by a conduit 100. Liquid accumulatingin the bottom portion of the vessel 88 is removed therefrom by a conduit102. The gas outlet connection of the separator 96 is connected to anexchanger 82 by a conduit 104. From the exchanger 82 the separatoroff-gas is connected by a conduit 106 to a conventional gas booster orcompressor 108. The discharge of the compressor 108 is connected by aconduit 110 to the heating coil 52 of the heater 58.

A closed cooling gas stream circuit is provided comprised of a coolinggas stream inlet header 112 which is connected to the vessels l6, l8 and20 by way of conduits 114, 116 and 118. The conduits 114,116 and 118 areconnected to the conduits 28, 30 and 32 and to the header112. Valves120, 122 and 124 are disposed in the conduits 114, 116 and 118respectively. A cooling gas stream outlet header 126 is provided forreceiving the cooling gas stream from the vessels 16, 18 and 20. Theheader 126 is connected by conduits 128, 130 and 132 to the conduits 36,38 and 40 respectively. Valves 134, 136 and 138 are disposed in theconduits 128, 130 and 132 respectively. The header 126 is connected tothe inlet of a conventional gas cooler 140, and the discharge connectionof the cooler 140 is connected by a conduit 142 to a conventional gasbooster or compressor 144. The discharge of the compressor 144 isconnected to the cooling gas stream inlet header 112 by a conduit 146.

The various valves described above may be any of a variety ofpneumatically, hydraulically or electrically operated control valves,either two-way or three-way. The sequential opening and closing of thevalves is automatically controlled by a conventional cycle controller,either time or temperature actuated. The cycle controller functions toopen certain of the valves and close others at the beginning of eachcycle so that the flow patterns of the inlet gas, regeneration gas andcooling gas streams passing through the system 10 are successivelychanged in a predetermined manner, as will be described furtherhereinbelow.

The regeneration and cooling gas stream circuits of the system 10 are ofthe closed type. As will be understood, other types of regeneration andcooling gas stream circuits known in the art as open circuits may beutilized. Further, when closed circuits of the type illustrated in thedrawing and described above are used, controls (not shown) are providedfor maintaining the gas volume circulated at a relatively constantlevel. In addition, volumwtemperature compensators of the type describedin U.S. Letters Pat. No. 3,405,507 dated Oct. 15, 1968, and assigned tothe assignee of this present invention, may be utilized in conjunctionwith the regeneration and cooling gas circuits to provide compensationfor volume and temperature changes therein. While three vesselscontaining beds of solid adsorbent have been described, it will beunderstood that a variety of cyclic adsorption systems may be utilizedfor carrying out the improved process of the present invention, whichsystems may include any number of adsorbent beds, open or closedregeneration gas and cooling gas stream circuits, etc.

OPERATION OF THE SYSTEM 10 In operation of the system 10, amulti-component inlet gas stream containing easy-to-regeneratecondensible components to be recovered flows into the system 10 by wayof the conduit 12 and into one of the vessels 16, 18 or 20. Let it beassumed that the adsorbent bed contained within the vessel 16 isadsorbing condensible components from the inlet gas stream. The inletgas stream flows by way of valve 22 and conduit 28 into the vessel 16.Valves 24 and 26 and conduits 30 and 32 serve a similar purpose when theadsorbent beds within the vessels 18 and 20 are contacted with the inletgas stream. In passing through the vessel 16, the inlet gas streamcontacts the solid adsorbent bed contained therein so that the desiredeasy-to-regenerate condensible components contained therein are adsorbedon the bed and removed from the gas stream. The resultant residue gasstream exits the vessel 16 by way of conduit 36 and valve 42, and ispassed into the residue gas stream header 34. Valves 44 and 46 andconduits 38 and 40 serve similarly to conduct the residue gas stream tothe header 34 during subsequent cycles. Fromthe header 34 the residuegas stream is removed from the system 10 by way of the conduit 48 fromwhere it is conducted to a point of use or further processing. I

When the bed of adsorbent material within the vessel 16 becomessubstantially loaded with adsorbed condensible components, it isregenerated by passing through it a heated regeneration gas stream. Letit be assumed thatthe adsorbent bed contained within the vessel 18 is tobe regenerated. A lean heated regeneration gas stream is passed from theregeneration gas stream inlet header 55 into the vessel 18 by way ofconduit 56, valve 62 and conduit 30. Conduits 54, 28, 58 and 32 andvalves 60 and 64 serve similarly when the adsorbent beds in the vessels16 and 20 are being regenerated. As the heated regeneration gas streampasses through the adsorbent bed contained within the vessel 18 it heatsthe adsorbent and causes both easyto-regenerate anddifficult-to-regenerate components adsorbed thereon to be desorbed intothe regeneration gas stream. The resulting rich regeneration gas streamcontaining the desorbed components'flows from the vessel 18 by way ofconduit 38, conduit and valve 76 into the rich regeneration gas streamoutlet header 66. Conduits 36, 68, 4t) and 72 and valves 74 and 78 servesimilarly during subsequent cycles. From the header 66 the richregeneration gas stream passes by way of conduit 80 into the heatexchanger 82. While passing through the heat exchanger 82 the richregeneration gas stream is cooled by exchange of heat with the leanregeneration gas stream. The cooled, ric'h regeneration gas stream thenpasses by way of conduit 84 to the lower portion of the vessel 88 andpasses upwardly through the vapor liquid contact trays 90 containedtherein. As the rich regeneration gas stream travels through the vessel88, it is contacted by liquid passing downwardly over the trays 90within the vessel 88, which liquid consists primarily ofeasy-to-regenerate components as will be described further herein. Asthe rich regeneration gas stream is intimately contacted by the liquidstream, a portion of the difficult-toregenerate components contained inthe rich regeneration gas stream is absorbed by the liquid stream andremoved from the rich regeneration gas stream. The absorbent liquidaccumulates in the bottom portion of the vessel88 and is removedtherefrom by way of conduit 102. From conduit 102, the liquid streamcontaining both difficult and easy-to-regenerate components therefrom bycontact with the liquid stream exits the vessel 88 by way of conduit 92and is passed to the inlet of the gas cooler 94. While passing throughthe gas cooler 94 easy-to-regenerate and additionaldifficultto-regenerate condensible components contained in theregeneration gas stream are condensed.

The resultant liquids and regeneration gas stream pass from the gascooler 94 by way of conduit 98 into the separator 96. While within theseparator 96 the liquids consisting primarily of easy-to-regeneratecomponents are separated from the regeneration gas stream therebyproducing a lean regeneration gas stream of minimumdifficult-to-regenerate component content. A continuous stream of theliquid consisting primarily of easy-to-regenerate components iswithdrawn from the separator 96 by way of the conduit 100 and passedinto the upper portion of the vessel 88. As previously described thisstream of liquid passes downwardly in the vessel 88 intimatelycontacting the rich regeneration gas stream and removingdifficult-to-regenerate components therefrom. The lean regeneration gasstream exits the separator 96 by way of a conduit 104 and is conductedto the heat exchanger 82 wherein it is preheated by heat exchange withthe rich regeneration gas stream as previously described. The preheatedlean regeneration gas stream then passes by way of conduit 106 into thesuction of thegas compressor 108. From the discharge of the compressor108, the lean regeneration gas stream passes by way of conduit 110through the heating coil 52 of the heater 50 wherein it is heated, andback to the regeneration gas stream inlet header 55 by way of conduit53.

When an adsorbent bed has been regenerated by contact with the heatedlean regeneration gas stream, it must be cooled before it can againcontact the inlet gas stream. Let it be assumed that the bed ofadsorbent material within the vessel 20 is in the process of beingcooled. A cooling gas stream is passed from the cooling gas stream inletheader 1 12 into the vessel 20 by way of conduit 118, valve 124 andconduit 32. Conduits 114, 28, 116 and 30, and valves 120 and 122 servesimilarly during subsequent cycles. The adsorbent bed contained withinthe vessel 20 is contacted by the cooling gas stream passingtherethrough which causes the bed to be cooled. From the vessel 20 thecooling 'gas stream is passed into the cooling gas stream outlet header126 by way of conduit 40, conduit 132 and valve 138. Conduits 36, 128,38 and 130 and valves 134 and 136 serve similar purposes. From theheader 126, the cooling gas stream passes into the gas cooler 140wherein heat removed from the adsorbent bed contained within the vessel20 by the cooling gas stream is removed from the cooling gas stream.From the gas cooler 140, the cooling gas stream is passed by way ofconduit 142 to the gas booster or compressor 144. The compressor 144functions to boost the pressure of the cooling gas stream so that itpasses by way of conduit 146 back to the cooling gas stream inlet header112.

As will be understood by those skilled in the art, the

' operation the vessel 88, cooler 94 and separator 96 is similar to aconventional rectification column. Due to the intimate contact of therich regeneration gas stream with a liquid stream consisting primarilyof easy-toregenerate components, a portion of the difficult-toregeneratecomponents are absorbed therefrom, and

by further cooling of the rich regeneration gas stream in the gas cooler94, additional difficult-to-regenerate components as well as the desiredeasy-to-regenerate components are condensed and separated from theregeneration gas stream. The liquid product stream removed from thevessel 88 by way of conduit 102 contains more of thedifficult-to-regenerate components as compared to prior art processes,and as a result, the regeneration gas stream remaining is leaner, or ofa difficult-to-regenerate component content which is less than thatobtainable by prior art processes. Due to the fact that the regenerationgas is leaner, an increased quantity of difficult-to-regeneratecomponents are removed from the adsorbent bed during the regenerationthereof, thereby increasing the capacity of the bed for the desiredeasy-to-regenerate components. For example, in processing a natural gasstream for the recovery of ethane, where the natural gas stream containsmethane, ethane and propane and heavier hydrocarbon compounds, themethane and ethane are easy to regenerate as compared to the propane andheavier hydrocarbon compounds. By the present invention, the leanregeneration gas stream contains a minimum quantity of propane andheavier hydrocarbon compounds, thereby removing a greater quantity ofthese compounds during the regeneration of the adsorbent beds whichresults in a greater ethane adsorption capacity and a longer adsorbentlife as compared to prior art processes used for recovering ethane fromnatural gas streams.

In order to present a clear understanding of the system 10, theadsorbent bed and valve sequence for three complete cycles is shown inTable 1 below.

TABLE I Adsorbent Bed and Valve Sequence For System 10 In order tofurther illustrate the improved process of the present invention, thefollowing examples are given.

EXAMPLE 1 For a natural gas stream of the composition given in Table I1below, at inlet conditions of F and 600 other conditions given above. a

psia, and using 4,000 pounds of activated carbon adsorbent per 1.0mmscf/day of inlet gas, the optimum cycle time for the recovery ofmaximum quantities of ethane is 30 minutes.

TABLE II Composition of Inlet Gas Stream Component Concentration (Molair 1.9 CO, 0.6 C 91.7 C, 3.6 C, 1.3 u 0.9

Total: 100.0

A regeneration gas stream of 375 scf/day/pound of adsorbent at 600 F and600 psia is required to regenerate the adsorbent. The composition of thelean regeneration gas stream produced in a conventional process whereinthe desorbed ethane and heavier hydrocarbon compounds are condensed andseparated therefrom at a temperature of 80 F and 600 psia is given inTable III below.

TABLE III Composition of Lean Regeneration Gas Stream by ConventionalProcess.

Component Concentration (M01911) C 64.0 C, 18.0 C, 12.0

- C 18.0 C 6.0 Total: 100.0

Contact of the adsorbentwith the lean regeneration gas stream given inTable Ill at 600 F and 600 psia results in the regeneration of theadsorbent to the values given in Table IV below at the cycle time andTABLE IV Quantity of Components Remaining Adsorbed After Regeneration byConventional Process Quantity of Component Remaining Component Adsorbed(lb Combonentl100 lb Adsorbent) C, 0.35 C, 0.55 C, 2.56

By the process of the present invention, at the same conditions givenabove, the lean regeneration gas stream is of the composition given inTable V below.

TABLEIV 6 LII Composition of Lean Regeneration Gas Stream by the Processof Present Invention Component Concentration (M0117) Upon contact of theadsorbent with the lean regeneration gas stream given in Table V at 600F and 600 psia, the adsorbent is regenerated to the values given inTable VI below.

' TABLE VI Quantity of Components Remaining Adsorbed After Regenerationby the Present Invention Quantity of Component Remaining ComponentAdsorbed (lb Component/ lb Adsorbent) C, 0.51 C, 0.84 C, 1.78

EXAMPLE 2 A 100 mmscf/day natural gas stream of the composition givengiven in Table VII below at inlet conditions of 400 psia and 100 F isprocessed by the system 10 shown in the drawing with the desiredeasy-toregenerate condensible components being ethane and thedifficult-to-regenerate components being propane and heavier hydrocarboncompounds contained therein.

TABLE VII Composition of Inlet Gas Stream Component Concentration (M01'12) Air 1.92 Carbon Dioxide 0.56 Methane 91.73 Ethane 3.61 Propane 1.29Iso-Butane 0.36 Normal Butane 0.30 lso-pentane 0.12 Normal Pentane 0.08Hexane Plus 0.03 Total: 100.00

133,000 pounds of activated carbon adsorbent material are contained ineach of the vessels 16, 18 and 20, and a cycle time of 30 minutes isused. During a first cycle as shown in TABLE I, the inlet gas streamcontacts the adsorbent bed contained within the vessel 16, and a 95mmscf/day residue gas stream is produced which is withdrawn from thesystem 10 by way of the conduit 48 at an average temperature of 120 F.Simultaneously, the adsorbent bed contained within the vessel 18 iscontacted with a 150 mmscf/day regeneration gas stream. The heatedregeneration gas stream is at an inlet temperature of 600 F and exitsthe vessel 18 at an initial temperature of 120 F, reaching a maximumtemperature of 550 F. The regeneration gas stream is cooled to atemperature of 100 F as it passes through the exchanger 82 and iscontacted with a 30,000 gallons/day stream of liquid having thecomposition given in Table VIII below as it leaves the vessel 88.

TABLE VIII Composition of Liquid Stream Exiting the Vessel 88 ComponentConcentration (Mol Carbon Dioxide 0.3 Methane 6.7 Ethane 15.0 Propane23.7 lso-Butane 12.0 Normal Butane 15.8 lso-Pentane 6.8 Normal Pentane6.5 Hexane Plus 13.2

Total: 100.0

The rich regeneration gas stream exiting the vessel 88 by way of conduit92 is cooled to a temperature of 80 F as it passes through the cooler 94resulting in the condensation of 30,000 gallons/day of liquid which isseparated from the remaining regeneration gas stream in the separator 96and passed by way of conduit 100 to the vessel 88. A 30,000 gallons/daystream of liquid hydrocarbons is withdrawn from the bottom portion ofthe vessel 88 by way of conduit 102.

The remaining lean regeneration gas stream having the composition givenin Table IX below exits the separator 96 and passes by way of conduit104 to the heat exchanger 82.

TABLE IX Composition of Lean Regeneration Gas Stream ComponentConcentration (Mol Air 20 Carbon Dioxide 0.72 Methane 94.5 Ethane 0.01Propane 2.4 Iso-Butane 0.25 Normal Butane 0.1 lso-Pentane 0.02 NormalPentane 0.00 Total:

bed of adsorbent contained within the vessel 20 is cooled to an averagetemperature of F.

Thus, the present invention is well adapted to carry out the objects andattain the ends and advantages mentioned as well as those inherenttherein. While presently preferred embodiments of the invention aregiven for the purpose of disclosure, numerous changes can be made whichwill readily suggest themselves to those skilled in the art and whichare encompassed within the spirit of the invention disclosed and claimedherein.

What is claimed is:

1. In an adsorption process for recovering easy-toregenerate condensiblecomponents from a multi-component inlet gas stream wherein a fixedadsorbent bed is contacted with said inlet gas stream so that bothdifficult and easy-to-regenerate condensible components containedtherein are adsorbed on said bed, then contacted with a heated leanregeneration gas stream so that said adsorbed components are desorbedtherefrom into said regeneration gas stream and a desorbed condensiblecomponent rich regeneration gas stream is produced, the desorbedcondensible components being condensed and removed from the richregeneration gas stream thereby producing a lean regeneration gasstream, and then contacted with a cooling gas stream so that it iscooled preparatory to again contacting said inlet gas stream, theimprovement in removing desorbed condensible components from said richregeneration gas stream which comprises:

a. intimately contacting said rich regeneration gas stream with a liquidstream consisting primarily of condensed easy-to-regenerate componentsso that a portion of the difficult-to-regenerate components containedtherein is adsorbed and removed therefrom by said liquid stream;

b. withdrawing said liquid stream from said process;

0. cooling the remaining rich regeneration gas stream from step (a) sothat easy-to-regenerate and remaining difficult-to-regeneratecondensible components contained therein are condensed; and

d. separating the components condensed in step (c) from saidregeneration gas stream thereby producing a lean regeneration gas streamof a minimum difficult-to-regenerate component content and a liquidstream consisting primarily of easy-toregenerate components for use instep (a).

2. The process of claim 1 which is further characterized to include thestep of separating the withdrawn liquid stream of step (b) intofractions to obtain an easy-to-regenerate component liquid product.

3. The process of claim 1 wherein the inlet gas stream is natural gas,the easy-to-regenerate condensible components contained therein aremethane and ethane and the difficult-to-regenerate condensiblecomponents contained therein are propane and heavier hydrocarboncompounds.

4. The process of claim 3 wherein the adsorbent is activated carbon.

5. A cyclic adsorption process for recovering easyto-regeneratecondensible components from a multicomponent inlet gas stream whichcomprises the steps of:

contacting one or more of a plurality of solid adsorbent beds with saidinlet gas stream so that both a. contacting said bed easyand,difficult-to-regenerate condensible components contained therein areadsorbed on said bed or beds;

simultaneously regenerating one or more other of said beds so thatpreviously adsorbed condensible components are removed therefrom,comprising the steps of:

or beds with a heated lean regeneration gas stream so that adsorbedcondensible componentsare desorbed from said bed or beds into saidregenerationrgas stream thereby producing are'generation gas stream richin said condensible components,

. intimately contacting said rich regeneration gas stream with a liquidstream consisting primarily of easy-to-reg'enerate components so that aportion of the difficult-to-regenerate components contained in said richregeneration gas stream is adsorbed and removed therefrom by said liquidstream,

c. withdrawing said liquid stream from said process,

d.- cooling the remaining rich regeneration gas stream from step (a) sothat easy-to-regenerate and remaining difficult-to-regeneratecondensible components contained therein are condensed,

e. separating the components condensed in step (d) from saidregeneration gas stream so that a lean regeneration gas stream ofminimum difficult-to-regenerate component content and a liquid streamconsisting primarily of easy-to- 7 1A regenerate components for use instep (b) are produced, f. heating the lean regeneration gas streamproduced instep (e), and g. recirculating said heated lean regenerationgas stream in a closed circuit into contact with said bed or beds;simultaneously contacting yet one or more other of said beds with acooling gas stream so that said bed I or beds are cooled preparatory tobeing contacted with said inlet gas stream; and

cycling said inlet gas stream, regeneration gas stream and cooling gasstream so that the bed or beds just contacted with said inlet gas streamare regenerated, the bed or beds just regenerated are contacted withsaid cooling gas stream and the bed or beds just contacted with saidcooling gas stream are contacted with said inlet gas stream.

6. The process of claim 5 which is further characterized to include thestep of separating the withdrawn liquid stream of step (0) intofractions to obtain an easy-to-regenerate component liquid product.

7. The process of claim 5 wherein the inlet gas stream is natural gas,the easy-to-regenerate condensible components contained therein aremethane and ethane and the difficult-to-regenerate condensiblecomponents contained therein are propane and heavier hydrocarboncompounds.

8. The process of claim 7 wherein the adsorbent is activated carbon.

2. The process of claim 1 which is further characterized to include thestep of separating the withdrawn liquid stream of step (b) intofractions to obtain an easy-to-regenerate component liquid product. 3.The process of claim 1 wherein the inlet gas stream is natural gas, theeasy-to-regenerate condensible components contained therein are methaneand ethane and the difficult-to-regenerate condensible componentscontained therein are propane and heavier hydrocarbon compounds.
 4. Theprocess of claim 3 wherein the adsorbent is activated carbon.
 5. Acyclic adsorption process for recovering easy-to-regenerate condensiblecomponents from a multi-component inlet gas stream which comprises thesteps of: contacting one or more of a plurality of solid adsorbent bedswith said inlet gas stream so that both easy and difficult-to-regeneratecondensible components contained therein are adsorbed on said bed orbeds; simultaneously regenerating one or more other of said beds so thatpreviously adsorbed condensible components are removed therefrom,comprising the steps of: a. contacting said bed or beds with a heatedlean regeneration gas stream so that adsorbed condensible components aredesorbed from said bed or beds into said regeneration gas stream therebyproducing a regeneration gas stream rich in said condensible components,b. intimately contacting said rich regeneration gas stream with a liquidstream consisting primarily of easy-to-regenerate components so that aportion of the difficult-to-regenerate components contained in said richregeneration gas stream is adsorbed and removed therefrom by said liquidstream, c. withdrawing said liquid stream from said process, d. coolingthe remaining rich regeneration gas stream from step (a) so thateasy-to-regenerate and remaining difficult-to-regenerate condensiblecomponents contained therein are condensed, e. separating the componentscondensed in step (d) from said regeneration gas stream so that a leanregeneration gas stream of minimum difficult-to-regenerate componentcontent and a liquid stream consisting primarily of easy-to-regeneratecomponents for use in step (b) are produced, f. heating the leanregeneration gas stream produced in step (e), and g. recirculating saidheated lean reGeneration gas stream in a closed circuit into contactwith said bed or beds; simultaneously contacting yet one or more otherof said beds with a cooling gas stream so that said bed or beds arecooled preparatory to being contacted with said inlet gas stream; andcycling said inlet gas stream, regeneration gas stream and cooling gasstream so that the bed or beds just contacted with said inlet gas streamare regenerated, the bed or beds just regenerated are contacted withsaid cooling gas stream and the bed or beds just contacted with saidcooling gas stream are contacted with said inlet gas stream.
 6. Theprocess of claim 5 which is further characterized to include the step ofseparating the withdrawn liquid stream of step (c) into fractions toobtain an easy-to-regenerate component liquid product.
 7. The process ofclaim 5 wherein the inlet gas stream is natural gas, theeasy-to-regenerate condensible components contained therein are methaneand ethane and the difficult-to-regenerate condensible componentscontained therein are propane and heavier hydrocarbon compounds.
 8. Theprocess of claim 7 wherein the adsorbent is activated carbon.